Trivalent antimony salts of organic acids and their pentavalent derivatives and methods of preparing same



United States Patent Ofice 2,996,528 TRIVALENT ANTIMONY SALTS OF ORGANIC ACIDS AND THEIR PENTAVALENT DERIVA- TIVES AND METHODS OF PREPARING SAME Burton S. Marks and Blaine 0. Schoepfle, Niagara Falls,

N .Y., assignors to Hooker Chemical Corporation, Niagara Falls, N.Y., a-corporation of New York No Drawing. Filed Oct. 4, 1957, Ser. No. 688,143

9 Claims. (Cl. 260-446) This invention relates to antimony salts of organic acids and their pentavalent derivatives and to methods of preparing same.

It is an object of this application to describe the novel reaction conditions necessary for the preparation of these antimony salts. It is a further object to describe the necessary reaction conditions, including reactants and physical conditions which will make the preparation of novel antimony salts feasible.

Further objects of the present invention are the production of antimony salts which are useful as flame-retarding additives. Illustrative of the flame retarding effectiveness of the antimony salts and derivatives thereare capable of being partially or completely hydrolyzed and condensed with suitable materials to polymeric products suitable for use as film forming materials, im-

pregnants, protective coatings and the like.

Further objects include the production of antimony salts of organic acids useful in organic syntheses.

Still further objects and advantages of the present invention will appear from the more detailed description set forth below, it being understood that this more detailed description is given by way of illustration and explanation only, and not by way of limitation, since various changes therein may be made by those skilled in the art, without departing from the scope and spirit of the present invention.

In accordance with the present invention it has been found that the reaction between organic carboxylic acids and antimony trioxide may be carried out readily, leading to the progressive formation of alkyl, aryl, and aralkyl salts of antimony; with conditions being controlled to determine the characteristics of the product obtained. These salts may be designated by the following general formula:

wherein Sb is trivalent antimony and wherein R is selected from the group consisting of an alkyl radical containing from 3 to 12 carbon atoms, an aryl radical, and an aralkyl radical. All of the compounds embraced Within this general formula are useful as flame-retardant additives, all can be prepared by the novel process of this invention and several of them are believed to be new compositions of matter. The salts thus formed are readily prepared and obtained in substantial yields. The carboxylic acid employed may be of the following types: aliphatic, such as the alkyl carboxylic acids, aryl and aralkyl carboxylic acids. Among the carboxylic acids which maybe used, and which represent the foregoing types are: butyric, valeric, caproic, heptylic, caprylic, pelargonic, capric, 2-ethylcaproic, cinnamic acid, and anisic acid. The corresponding antimony salts formed from reacting antimony trioxide with the previously listed carboxylic acids are antimony butyrate, antimony valerate, antimony caproate, antimony heptylate, antimony caprylate, antimony pelargonate, antimony caprate, antimony 2-ethylcaproate, antimony cinnamate, and antimony anisate.

While the invention has been referred to above by the reaction of an individual carboxylic acid with antimony trioxide, mixtures of carboxylic acids may be employed if desired, but control of the process is best carried out as further illustrated below in the examples by the use of individual carboxylic acids. The best controlled mixtures of acids used are those which have similar boiling points, eg caprylic and 2-ethylcaproic acids.

The antimony reactant employed is antimony trioxide.

The reaction that takes place may be illustrated by that which takes place between antimony trioxide and caprylic acid.

I until the equivalent of three moles of acid has been added per mole of antimony atom. The end of the reaction is signaled by no further evolution of water from the reaction mixture, and complies with the theoretical three moles of water.

In general the reaction is carried out by using a given molar quantity of antimony trioxide which is slurried in a large excess of the particular carboxylic acid employed. This reaction mixture is heated to reflux and maintained thusly while water is split out, removed from the reaction and collected in a suitable apparatus such as a Dean-Stark or Barrett water-trap. The end of the reaction is denoted by the elimination of the theoretical qualtity of water and further by the fact that the reaction will not eliminate additional water on refluxing.

The process is best carried-out by the use of excess carboxylic acid as the solvent. However, other solvents which are unreactive and which are of sufliciently high boiling point to allow the reaction to take place, and concurrent loss of water therefrom may also be employed.

The carboxylic acid used must be of sufficiently high boiling point, generally above C., to (1) allow the reaction to go smoothly with the theoretical loss of water and (2) to remain within the confines of the reaction mixture if an additional solvent other than the carboxylic acid is used. Furthermore, it is best that, the acid be insoluble or nonmiscible with water so that the reaction can be followed easily by noting the quantity of water eliminated.

The loss of water is usually noted by the time a reaction temperature of 160 C., is reached. Where the carboxylic acid is high boiling and much above 160 C. the reaction temperature rises as the water distills off. The elimination of water is direct, that is, no vacuum or drying agents are required for its removal. This is so because of' the high boiling point reactants employed which permits relatively high reaction temperatures, and a simple distillation of the water formed.

The product isobtained from the reaction mixture by Patented Aug. 15, 1961 i used and the reaction is maintained under a dry nitrogen blanket with careful temperature control in the purification step as outlined above. It should be pointed out that since many of the products are heavy viscous, nondistillableoils which can hydrolyze even in the air, good samples for analyses are generally difiicult to obtain. As aforesaid the products or antimony salts are in general easily hydrolyzed. The lower molecular weight carboxvylic acids yield products which hydrolyze even in the air.

Higher molecular weight carboxylic acids yield products much more resistant to hydrolysis.

As previously stated, this invention also has as one of its objects the preparation of the pentavalent derivatives of the trivalent antimony salts such as previously listed. Among such derivatives are antimony caproate dibromide, antimony caprylate dibromide, antimony 2- ethylcaproate dibromide, antimony caprylate dichloride, etc.

These pentavalent derivatives are readily prepared by the addition of a halogen such as bromine which may be added in a stoichiometric quantity to the corresponding trivalent antimony salt. The reaction may be carried out in an inert solvent such as carbon tetrachloride or directly between the reactants without any extraneous solvent. The reaction goes readily in the initial stages and may slow up as the last few percent of halogen is added. The reaction can be followed for example with bromine by the dissipation of the bromine color as the condensation proceeds.

The following examples illustrate some of the products and processes of the present invention:

Example 1.Preparatin of antimony caprylate (C H COO} Sb In a five hundred ml. flask fitted with thermometer, Barrett water trap, condenser and nitrogen inlet tube, was placed 250 grams of distilled caprylic acid and 29.2 grams (0.1 mole) of antimony oxide. The reaction mixture was heated at atmospheric pressure under a nitrogen blanket and at approximately 160 C., the evolution of water commenced. The reaction temperature slowly rises as the water distills off, and at approximately the boiling point of the caprylic acid, the theoretical evolution of water is realized, at which point the heating was discontinned.

The reaction mixture was cooled and then filtered, using a filter aid (Dicalite) to yield a yellow amber filtrate which was vacuum distilled (the temperature of the distilling mixture being maintained below 160 degrees centigrade) until the unreacted caprylic acid had distilled over. The resultant light brown colored residue, antimony caprylate, solidified at 52 degrees centigrade to a brownish white Waxy solid.

Analysis-Calculated for C H O Sb: Sb, 22.1. Found: 22.2.

Example 2.Preparati0n of antimony hlllyrate (C3H7COO)3Sb In 250 grams of butyric acid was suspended 29.2 grams (0.1 mole) of antimony oxide. The reaction mixture was heated under a nitrogen blanket at reflux for two hours, before the butyric acid was allowed to distill over slowly. The brownish colored liquid residue, antimony butyrate was found to hydrolyze rapidly in the presence of moist air. The antimony butyrate can be used without further purification, as a flame retarding agent ac- 4 cording to the teachings of said S.N. 688,lll,' filed of even date herewith.

Example 3.--Preparation of antimony cinnamate (C H CH=CHCOO Sb Amixture of- 250 grams of cinnamic acid and 29.2 grams (0.1 mole) of antimony oxide was heated together under a nitrogen blanket until the theoretical quantity of water had been distilled over.

The reaction mixture was vacuum distilled with the temperature kept below 200 degrees centigrade to remove the unreacted cinnamic acid. The amber colored liquid residue was poured while still hot and solidfied upon cooling. This product, antimony cinnamate, can also be used without further purification as a flame retarding agent according to the teachings of said S.N. 688,111, filed of even date herewith.

Example 4.-Preparan'on of antimony caproate (C5H11COO)3Sb In a five hundred milliliter flask fitted with thermometer, Barrett water trap, condenser, and nitrogen inlet tube was placed 250 milliliters of caproic acid and 29.2 grams (0.1 mole) of antimony oxide. The reaction mixture was heated to reflux under a nitrogen blanket until the theoretical amount of water had been evolved. The

amber-colored reaction mixture was filtered using Dicalite as a filter aid and the filtrate was then subjected to vacuum distillation to remove the excess caproic acid. The residue, a yellowish liquid, was antimony caprolate.

Analysis-Calculated for C H O Sb: Sb, 26.1. Found: 25.7. n "=1.4780.

Example 5.Preparati0n of antimony 2-ethylcaproate (CH CH CH CH CH(C H )COO);Sb

Antimony Z-ethyl caproate was prepared in the same manner as the preparation of antimony caprylate in Example 1, using instead of caprylic acid, Z-ethyl caproic acid. The product was also an amber-colored oil which tended to solidify on cooling.

Analysis-Calculated for C ,,H O Sb: Sb, 22.1. Found: 22.1. n :l.4735.

Example 6.-Preparation of antimony caprylate dibromide (C7H15COO) 3813131;

To a solution of 11 grams of antimony caprylate (0.02 m.) in carbon tetrachloride was added 3.2 grams (0.02 m.) of bromine. The reaction mixture readily dissipated the bromine color up to the addition of percent of the required bromine. The color from the last 20 percent of the bromine added was dissipated slowly on standing. The solvent was removed under water aspiration to yield a heavy orange oil. Further purification was not found to be feasible and the product was analyzed.

Analysis.--Calculated for C H O SbBl: Sb, 17.2. Found: 16.8. n =l.4950.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

1. A process for the direct preparation of trivalent antimony salts of organic acids consisting in reacting antimony trioxide with organic acids selected from the group consisting of alkyl, aryl, and aralkyl carboxylic acids which boil at temperatures of at least degrees centigrade which comprises heating the reactants at a temperature of at least 160 degrees centigrade at atmospheric pressure, and separating the water formed directly by a simple distillation from the reaction media.

2. A process according to claim 1 in which the high boiling organic acid is used in amount greater than that required for complete reaction with the antimony trioxide.

3. A process according to claim 1 in which the reaction is carried out in a high boiling, non-reactive media.

4. A eomposition ofmatter selected from theagt oup Reference! Cited in the tile of this patent congistingof antimony tributyrate, antimony triv crate, alnti'mony tricaproate, antimony triheptyla'te, antimony tri- UNITED STATES PATENTS caprylate, antimony tripelargonate, antimony tricaprat 1,888,187 v 1932 antimony tricinnamate, and fantimony trianieate. 5 2'488'268 Chmuamn 1949 Amimony tricaprylate; 2,511,013 Rust et ll. June 13, 1,50 v i v FOREIGN PATENTS 8. Antimony ti'ibutyrate. 1 213,285 Britain June 22, 1925 9'.Antimonytricinnamate. 10 

1. A PROCESS FOR THE DIRECT PREPARATION OF TRIVALENT ANTIMONY SALTS OF ORGANIC ACIDS CONSISTING IN REACTING ANTIMONY TRIOXIDE WITH ORGANIC ACID SELECTED FROM THE GROUP CONSISTING OF ALKYL, ARYL, AND ARALKYL CARBOXYLIC ACIDS WHICH BOIL AT TEMPERATURES OF AT LEAST 160 DEGREES CENTIGRADE WHICH COMPRISES HEATING THE REACTANTS AT A TEMPERATURE OF AT LEAST 160 DEGREES CENTIGRADE AT ATMOSPHERIC PRESSURE, AND SEPARATING THE WATER FORMED DIRECTLY BY A SIMPLE DISTILLATION FROM THE REACTION MEDIA. 